Largest ever tooth of ancient marine reptile discovered in Alps

The fossils of three giant marine reptiles that patrolled primordial oceans, called ichthyosaurs, have been discovered high up in the Swiss Alps, and include the largest ever tooth found for the species.

The specimens in question were unearthed between 1976 and 1990 during geological surveys, but were only recently analysed in detail in a study published in the Journal of Vertebrate Paleontology on Thursday.

With elongated bodies and small heads, the prehistoric leviathans weighed up to 80 tonnes (88 US tons) and grew to 20 metres, making them among the largest animals to have ever lived.

They first appeared 250 million years ago in the early Triassic, and a smaller, dolphin-like subtype survived until 90 million years ago. But the gigantic ichthyosaurs died out 200 million years ago.

Dated to 205 million years ago in the study, the three specimens in the current study were discovered at an altitude of 2,800 metres (9,100 feet). 

During their lifetimes the three swam in waters around the supercontinent Pangea, but the fossils kept rising due to plate tectonics and the folding of the Alps.

READ MORE: ‘Rare reptile skeleton’ going back 290 million years found in the US

'Particularly exciting'

There are two sets of skeletal remains. One consists of ten rib fragments and a vertebra, suggesting an animal some 20 metres long, which is more or less equivalent to the largest ichthyosaur to have been found, in Canada.

The second animal measured 15 metres, according to an estimate from the seven vertebrae found.

"From our point of view, however, the tooth is particularly exciting," said Martin Sander of the University of Bonn, lead author of the paper.

"Because this is huge by ichthyosaur standards: Its root was 60 millimetres (2.4 inches) in diameter - the largest specimen still in a complete skull to date was 20 millimetres and came from an ichthyosaur that was nearly 18 metres long."

While this could indicate a beast of epic proportions, it's more likely to have come from an ichthyosaur with particularly gigantic teeth, rather than a particularly gigantic ichthyosaur.

Current research holds that extreme gigantism is incompatible with a predatory lifestyle requiring teeth. That's why the largest known animal to have ever lived, the blue whale at 30 metres long and 150 tonnes, lacks teeth.

Blue whales are filter feeders, while the much smaller sperm whales, at 20 metres long and 50 tonnes, are hunters, and use more of their energy to fuel their muscles.

"Marine predators therefore probably can't get much bigger than a sperm whale," Sander said, though more fossils would need to be found to know for certain.

READ MORE: Paleontologists discover a multitude of dinosaurs in northern Italy